Measurement of residual stresses and solving the inverse problem to infer dislocation distributions

Residual stresses are present in the absence of external loads. All manufactured parts exhibit some degree of residual stress, which can drastically impact fatigue life. The simulation of these stresses has become exceedingly difficult as manufacturing processes have become more complex, and especially important as the desire to reduce over-designing to save on material costs has grown. As an alternative to computer simulations, a technique for measuring strains and then inferring an optimal dislocation distribution to generate the residual stress state is presented here. A continuum dislocation formulation is described in detail and optimization results are compared with a simpler discrete dislocation formulation. The ability of the optimization problem to match the full strain field is explored as regions of measurements and components of strain are withheld. The aim is to develop a technique to reduce the number of residual strain measurements necessary to fully characterize the residual stress in a manufactured part.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2017

Author dc:creator

• Swartz, Kenneth E

Contributors dc:contributor

• Beaudoin, Armand J.

• residual stress
• dislocations

Statement dc:rights

• Copyright 2016 Kenneth Swartz

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/95405

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/95405